Welcome to the strange and wonderful world of helicopters, a place where hoisting complete prefabricated houses, enacting death-defying rescues and generally venturing where no other machines can go is all in a day's work. See more flight pictures.

Ever since Daedalus fashioned wings of feathers and wax for himself and his son Icarus, humans have yearned to master powered, heavier-than-air flight. In the early 20th century, a few daring inventors turned the dream into reality by designing and building flying machines that actually lived up to their names. Everyone knows the story of the Wright brothers and their famed flight across the dunes of Kitty Hawk, N.C., so we won't dwell here on their accomplishments or how airplanes work. Instead, we want to focus on a lesser-known personality -- Igor Sikorsky -- and his vision of the modern helicopter: an aircraft without wings that achieves vertical flight from the rotation of overhead blades.

One thing that has characterized the helicopter since its invention in the 1930s has been the absurdity of the machine. The contraption simply looks unable to deliver on its promise, which is to fly up and down, backward and forward, right and left. The famous U.S. broadcast journalist Harry Reasoner discussed this apparent paradox in a 1971 commentary he delivered about the use of helicopters in the Vietnam conflict:

An airplane by its nature wants to fly. … A helicopter does not want to fly. It is maintained in the air by a variety of forces and controls working in opposition to each other, and if there is any disturbance in this delicate balance, the helicopter stops flying, immediately and disastrously. There is no such thing as a gliding helicopter.

Reasoner laid bare the fundamental reality of helicopters -- that the machines have complex designs and that flying them is extraordinarily complicated. The pilot has to think in three dimensions and must use both arms and both legs constantly to keep a helicopter in the air. Piloting a helicopter requires a great deal of training and skill, as well as continuous attention to the machine.

To fully appreciate this complexity, it helps to study the evolution of helicopters through the ages. How exactly did we get from floating, feathered Chinese tops to Black Hawks buzzing in the air? You'll see. Next.

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